The Spade seems to be the grandaddy of scoop/rollbar type anchors. I’ve often thought about it as the Ideal anchor. It’s possible it’s true.
The concave fluke was introduced by the french designer and the shank is (despite it’s long length) very optimum. As in low drag.
Many here have said the Spade and the Vulcan are the same. Not so. The length/width ratio (aspect ratio) is at least quite different but the most different component of the two anchors is the shank. With the Vulcan you get strength and w the Spade you get efficiency. But I don’t know what metal the Spade shank is made of. Reflecting the high price it could be high alloy steel and even stronger than the Vulcan. But the Vulcan looks very strong.
And ARA of Australia said nix on the mud scooper concave fluke and made the SARCA that is slightly convex. The highest holding power anchor I have I have is a flat fluke anchor. And the SARCA seems to set very quickly and without hesitation. Over time I’ve had lots of trouble w anchors setting and no trouble holding.